JPH1083995A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a trap from occurring due to the damage to a natural oxide film and to keep an emitter diffusion layer stable in carrier concentration, by a method wherein impurities are diffused into the surface layer of the base diffusion layer from a silicon film to form an emitter diffusion layer, after a natural oxide film formed on the surface of a base diffusion layer is removed. SOLUTION: A base diffusion layer 12 is formed on the front surface of a semiconductor substrate 11, an interlayer insulating film 13 is formed on the semiconductor substrate 11, and an emitter opening 14 is provided on the interlayer insulating film 13 so deep as to reach the base diffusion layer 12. Then, after a natural oxide film 15 formed on the surface layer of the semiconductor substrate 11 exposed on the base of the emitter opening 14 is removed, a silicon film 17 is formed on the semiconductor substrate 11 covering the interlayer insulating film 13. Impurities are diffused into the surface of the base diffusion layer 12 from the silicon film 16 to form an emitter diffusion layer 17. By this setup, impurities are diffused in a stable state for the formation of the emitter diffusion layer 16 without interposing a natural oxide film of an unstable bonding state, and carriers are set stable in injection efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method of manufacturing a semiconductor device, and more particularly to a semiconductor device having a bipolar transistor having an emitter formed by solid-phase diffusion from a silicon film, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, semiconductor devices represented by LSIs have been required to have higher integration and higher functions. For example, in order to achieve the above requirements in a bipolar transistor, it is necessary to increase the operation speed by shortening the base transit time and reducing the base resistance. Therefore, the base diffusion layer needs to contain carriers at a high concentration and be shallow.

However, in the emitter diffusion layer formed by diffusing impurities into the surface layer of the base diffusion layer, the carrier injection efficiency is reduced by increasing the concentration of the base diffusion layer.

Therefore, a polysilicon emitter technique shown in FIG. 7 has been proposed. A part of a method for manufacturing a semiconductor device using this technique will be described below. First, FIG. 7 (1)
As shown in (1), the base diffusion layer 12 is formed on the surface side of the semiconductor substrate 11 by, for example, ion implantation and subsequent thermal diffusion. Next, as shown in FIG. 7B, an interlayer insulating film 13 is formed on the semiconductor substrate 11, and the interlayer insulating film 13 is formed.
Then, an emitter opening 14 reaching the base diffusion layer 12 is formed. Thereafter, as shown in FIG.
Natural oxide film 1 on the surface of semiconductor substrate 11 exposed at the bottom of substrate 4
A silicon film 16 is formed on the semiconductor substrate 11 so as to cover the semiconductor substrate 11 and the interlayer insulating film 13. Thereafter, as shown in FIG. 7D, the impurity is solid-phase diffused from the silicon film 16 to the surface layer of the base diffusion layer 12 to form the emitter diffusion layer 17.

According to the above method, the activation efficiency of the impurity implanted into the emitter diffusion layer is increased as compared with the method of forming the emitter diffusion layer by ion implantation, and as a result, the carrier concentration can be increased. .

[0006]

However, in the above-described method of manufacturing a semiconductor device, since a silicon film is formed on a semiconductor substrate while a natural oxide film is left, there are the following problems. . That is, when the emitter diffusion layer is formed, the natural oxide film serves as a barrier for holes, and the natural oxide film has an effect of increasing the carrier injection efficiency. On the other hand, the natural oxide film is a very unstable layer having a part where the bond between oxygen and silicon is weak. For this reason, in the thermal diffusion step when forming the emitter diffusion layer, a part of the natural oxide film may be damaged. In particular, in order to form a shallow emitter diffusion layer, the semiconductor substrate is 1000
Since the substrate is heated to a high temperature of ° C., the above-described damage is easily generated. In such a case, when a reverse bias is applied between the emitter and the base, hot carriers are injected into the damaged portion and serve as a trap, thereby partially increasing the base current. Such a problem similarly occurs when a silicon oxide film is stacked on a natural oxide film for the purpose of increasing the carrier injection efficiency.

As described above, in the above-mentioned manufacturing method, the carrier injection efficiency in the emitter diffusion layer is very unstable, which causes a decrease in the reliability of the semiconductor device having the high-speed bipolar transistor as described above. ing.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. That is, the present invention is a method for manufacturing a semiconductor device in which a bipolar transistor is arranged on the surface side of a semiconductor substrate, and is characterized in that it is performed as follows. That is, an emitter opening reaching the base diffusion layer is formed in the interlayer insulating film formed on the semiconductor substrate having the base diffusion layer. Next, removal of the natural oxide film on the base diffusion layer surface at the bottom of the emitter opening,
A silicon film is formed. Then, an impurity is diffused from the silicon film to a surface layer of the base diffusion layer exposed at the bottom of the emitter opening to form an emitter diffusion layer.

In the above method, after the natural oxide film is removed, impurities are diffused from the silicon film to the surface layer of the base diffusion layer to form the emitter diffusion layer. Some are not damaged. Therefore, trapping due to hot carriers does not occur, stable carrier injection efficiency is maintained, and the impurity concentration in the emitter diffusion layer obtained by the diffusion has no diffusion barrier due to the natural oxide film. Stabilized in the layer.

In another method of the present invention, after the emitter opening is formed in an interlayer insulating film on a semiconductor substrate having a base diffusion layer, a silicon nitride based insulating film is formed on the semiconductor substrate at the bottom of the emitter opening. A thin film is formed. afterwards,
The formation of the silicon film and the formation of the emitter diffusion layer are performed in the same manner as in the first method.

In the above method, the emitter diffusion layer is formed with the silicon nitride-based insulating thin film provided between the silicon film and the base diffusion layer at the bottom of the emitter opening. The insulating thin film has a stronger bonding force than silicon oxide. For this reason, when forming the emitter diffusion layer, the insulating thin film is not damaged by heating in the diffusion of the impurity. For this reason, the insulating thin film serves as a barrier for holes, so that the efficiency of carrier injection in the emitter diffusion layer is ensured and trap generation due to hot carrier injection is suppressed.

In each of the above methods, a base diffusion layer is formed after removing a natural oxide film or forming an insulating thin film, and then an emitter diffusion layer is formed on a surface layer of the base diffusion layer. Is also good.

In the case described above, the step of forming the base diffusion layer is performed after the step of removing the natural oxide film and forming the insulating thin film. For this reason, even if a heat treatment is performed on the semiconductor substrate during the removal of the natural oxide film or the formation of the insulating thin film, the heat does not change the impurity profile of the base diffusion layer. Therefore, the carrier concentration in the emitter diffusion layer is stabilized, and the impurity profiles of the base diffusion layer and the emitter diffusion layer are maintained in a predetermined state as in the above-described methods.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to the manufacture of a bipolar transistor will be described below with reference to the drawings. Note that the same components as those of the related art described with reference to FIG. 7 are denoted by the same reference numerals. Here, in the manufacturing process of the bipolar transistor,
The step of forming the base diffusion layer and the emitter diffusion layer will be described.

(First Embodiment) FIG. 1 is a diagram showing a method of manufacturing a semiconductor device according to a first embodiment. First, FIG.
As shown in (1), a base diffusion layer 12 is formed on the front side of a semiconductor substrate 11. The semiconductor substrate 11 is made of, for example, silicon. Further, base diffusion layer 12 may be formed by ion implantation and thermal diffusion performed subsequently thereto, or may be formed by an epitaxial growth technique.

Next, as shown in FIG. 1B, an interlayer insulating film 13 is formed on the semiconductor substrate 11 and the interlayer insulating film 1 is formed.
3, an emitter opening 14 reaching the base diffusion layer 12 is formed. The interlayer insulating film 13 is made of, for example, silicon oxide, and is formed by a CVD method. The emitter opening 14 is formed by etching the interlayer insulating film 13 using a resist pattern (not shown) as a mask. The emitter opening 1 thus formed
The semiconductor substrate 11 (base diffusion layer 1) exposed at the bottom of
A natural oxide film 15 is generated on the surface layer of 2).

After that, as shown in FIG. 1C, the natural oxide film 15 on the surface layer of the semiconductor substrate 11 exposed at the bottom of the emitter opening 14 is removed. Here, the natural oxide film 15 is reduced and removed by performing a heat treatment at 900 ° C. in hydrogen gas (H ₂ ), or the natural oxide film 15 is removed by argon (Ar) sputtering.

In particular, when the natural oxide film 15 is removed by argon sputtering, the semiconductor substrate 11 is kept at 400 ° C.
Heat to a low temperature. Thus, the natural oxide film 15 is removed with low energy, and damage to the surface of the semiconductor substrate 11 is suppressed. Also, compared to other removal methods,
Since the heating temperature of the semiconductor substrate 11 is low, the base diffusion layer 1
The natural oxide film 15 is removed without changing the impurity profile of No. 2.

Next, as shown in FIG. 1D, a silicon film 16 made of polysilicon or amorphous silicon containing impurities for forming an emitter is formed on the semiconductor substrate 11 so as to cover the interlayer insulating film 13. I do. The silicon film 16 is formed by depositing a film containing no impurities by a CVD method and then introducing impurities by ion implantation, or by depositing a film containing impurities in advance by a CVD method (doped silicon). Suppose that

Thereafter, as shown in FIG. 1 (5), the silicon film 1 is subjected to a heat treatment at, for example, 900 ° C. for about 20 minutes.
6, the above-described impurities are solid-phase diffused into the surface layer of the base diffusion layer 12 to form the emitter diffusion layer 17.

In the method of forming the emitter diffusion layer 17 by solid-phase diffusion into the base diffusion layer 12 as described above, the emitter diffusion layer 17 is removed after the natural oxide film 15 is removed.
Is formed, a portion of the natural oxide film 15 is not damaged by heating in the diffusion of impurities, and no trap is generated. Therefore, the carrier concentration in the emitter diffusion layer 17 obtained by the diffusion is stabilized in the emitter diffusion layer 17. When the silicon film 16 is formed as doped polysilicon, the activation rate of the impurity in the silicon film 16 is high, so that the impurity implanted into the emitter diffusion layer 17 formed here is The activation rate is high, and as a result, the carrier injection efficiency can be increased.

(Second Embodiment) FIG. 2 is a diagram showing a method of manufacturing a semiconductor device according to a second embodiment. The second embodiment will be described with reference to the following drawings. First, as shown in FIG. 2 (1) and FIG. 2 (2), FIG.
As described with reference to (1) and FIG. 1 (2),
Forming a base diffusion layer 12 on the front side of the semiconductor substrate 11;
The emitter opening 14 is formed on the interlayer insulating film 13 formed on the semiconductor substrate 11.

Next, as shown in FIG. 2C, a silicon film 16 is formed on the semiconductor substrate 11 with the natural oxide film 15 remaining on the surface layer of the semiconductor substrate 11. It is assumed that the silicon film 16 formed here is polysilicon containing no impurities.

Thereafter, as shown in FIG.
By performing a heat treatment at a temperature of about 0 ° C., oxygen constituting the native oxide film 15 is absorbed in the silicon film 16 and the native oxide film 15 is removed.

Next, as shown in FIG. 2 (5), after impurities are introduced into the silicon film 16 by ion implantation,
For example, by performing heat treatment at 900 ° C. for about 20 minutes, impurities are solid-phase diffused from the silicon film 16 to the surface layer of the base diffusion layer 12 to form the emitter diffusion layer 17.

As described above, the method of forming the emitter diffusion layer 17 by solid-phase diffusion into the base diffusion layer 12 also removes the native oxide film 15 and removes the emitter diffusion layer similarly to the method of the first embodiment. Since the layer 17 is formed, the carrier concentration in the emitter diffusion layer 17 can be stabilized.

(Third Embodiment) FIG. 3 is a view showing a method of manufacturing a semiconductor device according to a third embodiment. The third embodiment will be described with reference to the following drawings. First, as shown in FIGS. 3 (1) and 3 (2), FIG.
As described with reference to (1) and FIG. 1 (2),
Forming a base diffusion layer 12 on the front side of the semiconductor substrate 11;
An emitter opening reaching the base diffusion layer is formed in an interlayer insulating film formed on the semiconductor substrate.

Thereafter, as shown in FIG. 3C, a silicon nitride-based insulating thin film 30 is formed on the semiconductor substrate 11 exposed at the bottom of the emitter opening 14. This insulating thin film 30 is formed by performing a heat treatment at 900 ° C. in an oxygen dinitride (N ₂ O) atmosphere, or nitriding a silicon oxide film formed by a thermal oxidation method at a temperature of 1000 ° C. May be performed to form a film. In the case where the silicon oxide film is nitrided to form the silicon nitride-based insulating thin film 30, reoxidation is performed as necessary to reduce the interface state.

The insulating thin film 30 may be formed as follows. That is, a silicon nitride film is formed on the exposed surface of the semiconductor substrate 11 at a temperature of about 750 ° C., and then oxidized in ozone (O ₃ ).
The silicon nitride film is oxidized at a low temperature of about 00 ° C. to form an insulating thin film 30 made of silicon nitride oxide. By forming the insulating thin film 30 at such a low temperature, a change in the concentration profile of the base diffusion layer 12 during the film forming process of the insulating thin film 30 is prevented.

The exposed surface of the semiconductor substrate 11 on which the insulating thin film 30 is formed is covered with the native oxide film 15. Therefore, the insulating thin film 30 is laminated on the natural oxide film 15. However, in order to further stabilize the carrier injection efficiency in the emitter diffusion layer to be formed later, the insulating thin film 30 may be formed after removing the natural oxide film 15. In this case, the natural oxide film 15 is removed in the same manner as described in the first embodiment with reference to FIG.

Next, as shown in FIGS. 3 (4) and 3 (5), in the same manner as described with reference to FIGS. 1 (4) and 1 (5) in the first embodiment, From the silicon film 16 formed on the substrate 11 so as to cover the interlayer insulating film 13,
Impurities are diffused into the surface layer of the base diffusion layer 12 to form the emitter diffusion layer 17.

In the method of forming the emitter diffusion layer 17 by solid-phase diffusion into the base diffusion layer 12 as described above, a silicon nitride-based material is formed between the silicon film 16 and the base diffusion layer 12 at the bottom of the emitter opening 14. The emitter diffusion layer 17 is formed in a state where the insulating thin film 30 is provided. The insulating thin film 30 has a stronger bonding force than silicon oxide. From this, the emitter diffusion layer 17
Is formed, the insulating thin film 30 is not damaged by heating in the diffusion of impurities. For this reason, the carrier injection efficiency in the emitter diffusion layer is stabilized, and the insulating thin film 30 serves as a hole barrier, ensuring the carrier injection efficiency and suppressing trapping due to hot carrier injection. .

(Fourth Embodiment) FIG. 4 is a view showing a method of manufacturing a semiconductor device according to a fourth embodiment. The manufacturing method of the fourth embodiment shown in this figure is a method in which the order of performing the step of forming the base diffusion layer in the first embodiment described with reference to FIG. 1 is changed, and the other steps are the same as those of the first embodiment. This is performed according to the embodiment.

That is, first, as shown in FIG. 4A, an interlayer insulating film 13 is formed on a semiconductor substrate 11, and an emitter opening 14 is formed in the interlayer insulating film 13. next,
As shown in FIG. 4B, the natural oxide film 15 on the exposed surface of the semiconductor substrate 11 is removed. Next, as shown in FIG. 4C, a silicon film 16 is formed on the semiconductor substrate 11 so as to cover the interlayer insulating film 13.

Thereafter, as shown in FIG. 4D, a base diffusion layer 12 is formed on the surface layer of the semiconductor substrate 11. Here, the base diffusion layer 1 is formed by performing ion implantation from above the silicon film 16 and subsequently performing heat treatment.
Form 2

Next, as shown in FIG. 4 (5), an emitter diffusion layer 17 is formed on the surface layer of the base diffusion layer 12 by impurity diffusion from the silicon film 16. In this case, the impurities in the silicon film 16 are introduced by ion implantation after the base diffusion layer 12 is formed, so that the base diffusion layer 1 is formed.
In the thermal diffusion at the time of forming 2, it is possible to prevent the emitter impurities from being simultaneously diffused. The diffusion of the emitter impurity and the formation of the base diffusion layer can be performed simultaneously by a single heat treatment (by optimizing the conditions). In this case, it is possible to introduce impurities simultaneously with the formation of the silicon film. This is because the formation of the silicon film can be performed at a low temperature of about 600 ° C., so that the influence on the base impurity profile is almost negligible.

The base diffusion layer 12 is formed by forming a native oxide film 15 as shown in FIG.
In addition, as shown in FIG. 4C, it may be performed before the silicon film 16 is formed. In this case, the silicon film 16 formed in FIG. 4C may contain impurities in advance.

In the method of forming emitter diffusion layer 17 by solid-phase diffusion into base diffusion layer 12 as described above, the step of forming base diffusion layer 12 is performed after the step of removing native oxide film 15. Therefore, even if the semiconductor substrate 11 is subjected to a heat treatment when the natural oxide film 15 is removed, the heat does not change the impurity profile of the base diffusion layer 12. Therefore, similarly to the methods of the first to third embodiments, the carrier concentration in the emitter diffusion layer 17 is stabilized, and the impurity profiles of the base diffusion layer 12 and the emitter diffusion layer 17 are secured in a predetermined state. You.

(Fifth Embodiment) FIG. 5 is a diagram showing a method of manufacturing a semiconductor device according to a fifth embodiment. The manufacturing method of the fifth embodiment shown in this figure is a method in which the order of performing the step of forming the base diffusion layer in the second embodiment described with reference to FIG. 2 is changed, and the other steps are the same as those of the second embodiment. This is performed according to the embodiment.

First, as shown in FIG. 5A, an interlayer insulating film 13 is formed on a semiconductor substrate 11, and an emitter opening 14 is formed in the interlayer insulating film 13. next,
As shown in FIG. 5B, a silicon film 16 is formed on the semiconductor substrate 11 so as to cover the interlayer insulating film 13 and the native oxide film 15.
Is formed. Thereafter, as shown in FIG. 5C, the natural oxide film 15 on the exposed surface of the semiconductor substrate 11 is removed by heat treatment.

After that, as shown in FIG. 5D, a base diffusion layer 12 is formed on the surface layer of the semiconductor substrate 11. Here, the base diffusion layer 1 is formed by performing ion implantation from above the silicon film 16 and subsequently performing heat treatment.
Form 2

Next, as shown in FIG. 5E, an emitter diffusion layer 17 is formed on the surface layer of the base diffusion layer 12 by diffusing impurities from the silicon film 16. That is, after introducing impurities into the silicon film 16 by ion implantation, the impurities in the silicon film 16 are diffused into the surface layer of the base diffusion layer 12 by performing a heat treatment to form the emitter diffusion layer 17.

In the method of forming the emitter diffusion layer 17 by solid-phase diffusion into the base diffusion layer 12 as described above, the carrier concentration in the emitter diffusion layer 17 is stabilized as in the fourth embodiment. And base diffusion layer 1
2 and the impurity profile of the emitter diffusion layer 17 are maintained in a predetermined state.

(Sixth Embodiment) FIG. 6 is a diagram showing a method of manufacturing a semiconductor device according to a sixth embodiment. The manufacturing method of the sixth embodiment shown in this figure is a method in which the order of performing the step of forming the base diffusion layer in the third embodiment described with reference to FIG. 3 is changed, and the other steps are the same as those of the third embodiment. This is performed according to the embodiment.

That is, first, as shown in FIG. 6A, an interlayer insulating film 13 is formed on a semiconductor substrate 11, and an emitter opening 14 is formed in the interlayer insulating film 13. next,
As shown in FIG. 6 (2), the silicon nitride-based insulating thin film 30 is overlaid on the natural oxide film 15 on the exposed surface of the semiconductor substrate 11 or with the natural oxide film 15 removed.
Is formed.

Thereafter, as shown in FIG. 6C, a base diffusion layer 12 is formed on the surface layer of the semiconductor substrate 11. Here, the base diffusion layer 12 is formed by performing ion implantation from above the silicon film 16 and performing a subsequent heat treatment.
To form

Next, as shown in FIG. 6D, a silicon film 16 is formed on the semiconductor substrate 11 so as to cover the interlayer insulating film 13.
Is formed. Thereafter, as shown in FIG. 6E, an emitter diffusion layer 17 is formed on the surface layer of the base diffusion layer 12 by impurity diffusion from the silicon film 16.

The base diffusion layer 12 is formed by forming a silicon film 16 as shown in FIG.
In addition, as shown in FIG. 6 (5), it may be performed before the emitter diffusion layer 17 is formed.

In the method of forming the emitter diffusion layer 17 by solid-phase diffusion into the base diffusion layer 12 as described above, the carrier concentration in the emitter diffusion layer 17 is reduced as in the fourth and fifth embodiments. It is stabilized and the impurity profiles of the base diffusion layer 12 and the emitter diffusion layer 17 are maintained in a predetermined state. Further, similarly to the third embodiment, the efficiency of carrier injection into the emitter diffusion layer 17 is improved. Therefore, high efficiency and stable carrier injection efficiency can be realized while suppressing trap generation due to hot carrier injection.

[0050]

As described above, according to the method of manufacturing a semiconductor device of the present invention, the impurity is diffused from the silicon film to the surface layer of the base diffusion layer after the natural oxide film on the surface of the base diffusion layer is removed. By forming the diffusion layer, it is possible to prevent generation of traps due to damage of the natural oxide film and to stabilize the carrier concentration in the emitter diffusion layer. Therefore, the reliability of the semiconductor device having the high-speed bipolar transistor can be improved.

Further, by forming the emitter diffusion layer in a state where a silicon nitride-based insulating thin film is provided between the silicon film and the base diffusion layer at the bottom of the emitter opening,
The insulating thin film in a stable bonded state can be used as a hole barrier. For this reason, it is possible to increase the carrier injection efficiency in the emitter diffusion layer in a stable state, and it is possible to improve the reliability of the semiconductor device having the high-speed bipolar transistor.

Further, in each of the above methods, the removal of the natural oxide film and the formation of the insulating thin film are performed to form an emitter diffusion layer on the surface layer of the base diffusion layer formed. It is possible to prevent a change in the impurity profile of the base diffusion layer due to the heat treatment during the formation of the insulating thin film. For this reason, in addition to the effects of the above-described methods, it becomes possible to secure the impurity profiles of the base diffusion layer and the emitter diffusion layer in a predetermined state.

[Brief description of the drawings]

FIG. 1 is a sectional process view showing a first embodiment.

FIG. 2 is a sectional process view showing a second embodiment.

FIG. 3 is a sectional process view showing a third embodiment.

FIG. 4 is a sectional process view showing a fourth embodiment.

FIG. 5 is a sectional process view showing a fifth embodiment.

FIG. 6 is a sectional process view showing a sixth embodiment.

FIG. 7 is a sectional process view showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Semiconductor substrate 12 Base diffusion layer 13 Interlayer insulating film 14 Emitter opening 15 Natural oxide film 16 Silicon film 17 Emitter diffusion layer 30 Insulating thin film

Claims (7)

[Claims] 1. A method of manufacturing a semiconductor device, comprising: forming a bipolar transistor on a front surface of a semiconductor substrate; forming a base diffusion layer on the front surface of the semiconductor substrate; and forming an interlayer insulating film on the semiconductor substrate. Forming an emitter opening reaching the base diffusion layer in the interlayer insulating film; and removing a natural oxide film generated in a surface layer of the semiconductor substrate exposed at a bottom of the emitter opening; Forming a silicon film on the semiconductor substrate in a state of covering the surface of the semiconductor substrate from which the natural oxide film has been removed, and diffusing impurities from the silicon film to a surface layer of the base diffusion layer to form an emitter diffusion layer Forming a semiconductor device. 2. A method of manufacturing a semiconductor device in which a bipolar transistor is formed on a surface of a semiconductor substrate, comprising: forming a base diffusion layer on the surface of the semiconductor substrate; and forming an interlayer insulating film on the semiconductor substrate. Forming an emitter opening reaching the base diffusion layer in the interlayer insulating film; and forming a silicon film on the semiconductor substrate so as to cover a surface of the semiconductor substrate exposed at a bottom of the emitter opening. Removing the natural oxide film by absorbing oxygen constituting the natural oxide film generated in the surface layer of the semiconductor substrate at the bottom of the emitter opening by the heat treatment into the silicon film; Introducing an impurity into the film, and diffusing the impurity from the silicon oxide film into the surface layer of the base diffusion layer to form an emitter diffusion layer; A method of manufacturing a semiconductor device. 3. A method for manufacturing a semiconductor device, wherein a bipolar transistor is formed on a surface side of a semiconductor substrate, comprising: forming a base diffusion layer on the surface side of the semiconductor substrate; and forming an interlayer insulating film on the semiconductor substrate. Forming an emitter opening reaching the base diffusion layer in the interlayer insulating film; forming a silicon nitride-based insulating thin film on a semiconductor substrate exposed at the bottom of the emitter opening; Forming a silicon film on the conductive thin film, and diffusing impurities from the silicon film through the insulating wire thin film to the surface layer of the base diffusion layer to form an emitter diffusion layer. Semiconductor device manufacturing method. 4. A method for manufacturing a semiconductor device, wherein a bipolar transistor is formed on a front side of a semiconductor substrate, wherein an interlayer insulating film is formed on the semiconductor substrate, and the emitter opening reaches the semiconductor substrate in the interlayer insulating film. Forming a natural oxide film formed on a surface layer of the semiconductor substrate exposed at the bottom of the emitter opening; and covering the surface of the semiconductor substrate from which the natural oxide film has been removed. A step of forming a silicon film on the semiconductor substrate; a step of forming a base diffusion layer in a surface layer of the semiconductor substrate by ion implantation after removing the natural oxide film; and a step of forming the base diffusion layer from the silicon film. Forming an emitter diffusion layer by diffusing impurities into a surface layer of the semiconductor device. 5. A method for manufacturing a semiconductor device, wherein a bipolar transistor is formed on a front surface side of a semiconductor substrate, wherein an interlayer insulating film is formed on the semiconductor substrate, and the emitter opening reaches the semiconductor substrate in the interlayer insulating film. Forming a silicon film on the semiconductor substrate so as to cover the surface of the semiconductor substrate exposed at the bottom of the emitter opening; and heat treating the semiconductor substrate at the bottom of the emitter opening. Removing the natural oxide film by absorbing oxygen constituting the natural oxide film generated in the surface layer into the silicon film; and removing the natural oxide film, and then ion-implanting the surface layer of the semiconductor substrate. Forming a base diffusion layer in the silicon film, introducing impurities into the silicon film, and introducing impurities into the surface layer of the base diffusion layer from the silicon film. The method of manufacturing a semiconductor device which is characterized in that the by diffusing and forming an emitter diffusion layer. 6. A method for manufacturing a semiconductor device, wherein a bipolar transistor is formed on a front surface side of a semiconductor substrate, wherein an interlayer insulating film is formed on the semiconductor substrate, and the emitter opening reaches the semiconductor substrate in the interlayer insulating film. Forming a silicon nitride-based insulating thin film on the semiconductor substrate exposed at the bottom of the emitter opening; forming a silicon film on the insulating thin film; Forming a base diffusion layer on the surface layer of the semiconductor substrate by ion implantation after forming the conductive thin film; and forming an emitter by diffusing impurities from the silicon film through the insulating thin film to the surface layer of the base diffusion layer. Forming a diffusion layer. 7. An interlayer provided on the semiconductor substrate in a shape having a base diffusion layer provided on a surface layer of the semiconductor substrate and an emitter opening on the base diffusion layer to expose a part of the base diffusion layer. A semiconductor device comprising: an insulating film; a silicon film provided on the semiconductor substrate exposed from an emitter opening of the interlayer insulating film; and an emitter diffusion layer provided on a surface layer of the semiconductor substrate below the silicon film. 2. The semiconductor device according to claim 1, wherein a silicon nitride-based insulating thin film is provided between the silicon film and the semiconductor substrate.